Navigate to Settings > Customisation to update the HTML header for each PDF.

The default snippet, which you can change, is listed below for reference.

<div class="header py-1 m-0 mb-4 bg-white border-top border-bottom">
<div class="row">
<div class="col-md-4">
<div class="logo">
<a href="#"
><img
src="https://d103wip7pc0e5p.cloudfront.net/dev/school/logo/cms/2020/a5e1ddeb-7a09-49d4-a01b-7f86f3d031d2.png"
style="max-width: 100%; object-fit: cover"
/></a>
</div>
</div>
<div class="col-md-4">
<p class="m-0 pt-2">123 Pennant Hills Road PENNANT HILLS NSW 2120 Australia</p>
</div>
<div class="col-md-4">
<p class="m-0 pt-2">
registrar@test.nsw.edu.au<br />
http://www.test.nsw.edu.au/<br />
<!---->
</p>
</div>
</div>
</div>